Multi-phase polymerization process

ABSTRACT

The present invention provides a multi-phase polymerization process for making a water insoluble polymer. The process includes (1) providing a mixture comprising carbon dioxide and an aqueous phase, and containing a monomer and a polymerization initiator, and (2) polymerizing the monomer in the reaction mixture. The monomer may be a hydrocarbon or a fluorinated monomer. The polymerization initiator may be soluble in the aqueous phase, soluble in carbon dioxide, or insoluble in both the aqueous phase and carbon dioxide, such that the initiator forms a separate phase. 
     The present invention also provides multi-phase polymerization reaction mixtures useful in the process of making water insoluble polymers.

FIELD OF THE INVENTION

The present invention relates to a multi-phase polymerization processfor making polymers in the presence of carbon dioxide.

BACKGROUND OF THE INVENTION

Polymerization processes can generally be classified into two basictypes: homogeneous and heterogeneous processes. This classification isusually based on whether the initial reaction mixture or the finalreaction mixture or both is homogeneous or heterogeneous. Somepolymerization systems which start out as homogeneous may becomeheterogeneous as the polymerization reaction proceeds, due to theinsolubility of the resulting polymer in the polymerization media.

Heterogeneous polymerizations are used extensively as a means to controlthe thermal and viscosity problems associated with mass and solutionpolymerizations. Emulsion polymerization is a heterogeneouspolymerization process used by industry to polymerize a variety ofmonomers. The use of a water or water-rich phase in emulsionpolymerizations is common. Polymers commonly formed by emulsionpolymerization include acrylics, styrenics, polyvinylchloride,styrene-butadiene rubber, ethylene-propylene-diene terpolymer,polystyrene, acrylonitrile-butadiene-styrene copolymers, neoprenerubber, ethylene-vinylacetate copolymers, styrene-maleic anhydridepolymers, poly(tetrafluoroethylene), tetrafluoroethylene copolymers,poly(vinylfluoride), and the like.

Heterogenous polymerizations employing a carbon dioxide phase haverecently been proposed. Carbon dioxide is a desirable media forpolymerization because it is inexpensive and environmentally safe. U.S.Pat. No. 5,312,882 to DeSimone et al. proposes a heterogenouspolymerization process for the synthesis of water-insoluble polymers incarbon dioxide. The heterogenous reaction mixture includes carbondioxide, monomer, and surfactant. The disclosed heterogenous reactiondoes not include a water or water-rich phase. U.S. Pat. No. 4,933,404 toBeckman et al. proposes a microemulsion polymerization system includinga low polarity fluid which is a gas at standard temperature and asecond, water phase. The monomer is soluble in the water phase, and ispolymerized in the micelles to produce a water soluble polymer.

Carbon dioxide has also been employed in polymerization systems for thepolymerization of hydrocarbon and fluorinated monomers. For example,U.S. Pat. No. 3,522,228 to Fukui et al. proposes the polymerization ofvinyl monomers using hydrocarbon polymerization initiators in carbondioxide. U.S. Pat. No. 4,861,845 to Slocum et al. discloses a gas phasepolymerization of tetrafluoroethylene and other fluoromonomers dilutedwith gaseous carbon dioxide. PCT Publication No. WO 93/20116 to theUniversity of North Carolina at Chapel Hill discloses processes formaking fluoropolymers which include solubilizing a fluoromonomer in asolvent comprising carbon dioxide. The fluoromonomers are selected fromthe group consisting of fluoroacrylate monomers, fluoroolefin monomers,fluorostyrene monomers, fluorinated vinyl ether monomers, andfluoroalkylene oxide monomers.

There remains a need in the art for a method of making polymers whichavoids the use of expensive or environmentally objectionable solventsand which are relatively easily separable from the polymer produced. Inaddition, it would be desirable to provide polymerization processes,particularly for the polymerization of fluorinated monomers, which iscapable of commercialization in conventional polymerization equipment.

SUMMARY OF THE INVENTION

As a first aspect, the present invention provides a multi-phasepolymerization process for making water insoluble polymers. The processincludes (1) providing a reaction mixture comprising carbon dioxide andan aqueous phase, and containing a monomer and a polymerizationinitiator, and (2) polymerizing the monomer. The monomer is generallysolubilizable in carbon dioxide. The polymerization process is usefulfor the polymerization of hydrocarbon monomers and fluorinated monomers.The polymerization initiator may be soluble in the aqueous phase,soluble in carbon dioxide, or insoluble in both the aqueous phase andcarbon dioxide, such that the initiator forms a separate phase, with orwithout a surfactant.

As a second aspect, the present invention provides a multi-phase mixtureincluding carbon dioxide and an aqueous phase, and containing a monomerand a polymerization initiator, with or without a surfactant.

As a third aspect, the present invention provides a multi-phasepolymerization process for making water insoluble polymers including thesteps of providing a reaction mixture including carbon dioxide and anaqueous phase, and a water insoluble polymer; and separating the polymerfrom the reaction mixture, with or without a surfactant.

As a fourth aspect, the present invention provides a multi-phase mixtureproduced from the multi-phase polymerization of a monomer. The reactionmixture includes carbon dioxide and an aqueous phase, and a waterinsoluble polymer, with or without a surfactant.

The foregoing and other aspects of the present invention are explainedin detail in the detailed description set forth below.

DETAILED DESCRIPTION OF THE INVENTION

As used herein, the term "supercritical" has its conventional meaning inthe art. A supercritical fluid (SCF) is a substance above its criticaltemperature and critical pressure (or "critical point"). Compressing agas normally causes a phase separation and the appearance of a separateliquid phase. However, if the fluid is in a supercritical state,compression will only result in density increases: no liquid phase willbe formed. The use of supercritical fluids for carrying outpolymerization processes has received relatively little attention. Theterm "fluoropolymer," as used herein, has its conventional meaning inthe art. See generally Fluoropolymers (L. Wall, Ed.1972)(Wiley-Interscience Division of John Wiley & Sons); See alsoFluorine-Containing Polymers, 7 Encyclopedia of Polymer Science andEngineering 256 (H. Mark et al. Eds., 2d Ed. 1985). Likewise, the term"fluoromonomer" or "fluorinated monomer" refers to fluorinated precursormonomers employed in the synthesis of fluoropolymers.

The processes of the present invention are carried out in a mixturecomprising a carbon dioxide phase and an aqueous phase. The carbondioxide phase may be in a gaseous, liquid or supercritical state. Aswill be appreciated by those skilled in the art, all gases have acritical temperature above which the gas cannot be liquified byincreasing pressure, and a critical pressure, or pressure which isnecessary to liquify the gas at the critical temperature. For example,carbon dioxide in its supercritical state exists as a form of matter inwhich its liquid and gaseous states are indistinguishable from oneanother. For carbon dioxide, the critical temperature is about 31° C.and its critical pressure is greater than about 1070 psi. Liquid carbondioxide may be obtained at temperatures of from about 31° C. to about-55° C.

The aqueous phase of the mixture typically comprises water, but mayinclude other additives such as acids, bases, salts, pH buffers,alcohols, and the like. Suitable additives are known to those skilled inthe art.

The ratio of carbon dioxide phase to aqueous phase in the reactionmixture will depend upon the monomer or comonomers to be polymerized,and the reaction conditions. Generally, the ratio of carbon dioxidephase to aqueous phase in the reaction mixture will be between about1:99 and about 99:1 parts by volume.

The mixture may also include one or more co-solvents. Suitablecosolvents will not cause excessive chain transfer. Illustrative ofco-solvents which may be employed in the processes of the presentinvention include but are not limited to C₂ -C₈ hydrocarbons, C₁ -C₈alcohols, methylene chloride, toluene, cyclohexane, methylethylketone,acetone, ethylacetate, tetrahydrofuran, perfluorocarbons,hydrofluorocarbons, perfluoroalkyl sulfides, and the like.

The monomers useful in the processes of the present invention includeany suitable monomer known to those skilled in the art which is capableof producing a water insoluble polymer. The processes of the presentinvention are particularly suitable for the polymerization ofhydrocarbon and fluorinated monomers. The monomers may be in a gaseousor liquid state. Generally, the monomers useful in the processes of thepresent invention are capable of free radical polymerization.

The hydrocarbon monomers which are useful in the processes of thepresent invention include any suitable hydrocarbon monomer known tothose skilled in the art which are capable of producing water insolublepolymers. Specific examples of suitable hydrocarbon monomers include,but are not limited to, vinyl monomers such as vinyl chloride and vinylacetate; ethylene; propylene; acrylonitrile; dienes such as isoprene,chloroprene, and butadiene; styrenics such as styrene and t-butylstyrene; acrylic monomers such as alkyl(meth)acrylates, alkylacrylates,methacrylic acid, and acrylic acid; acrylamides; maleic anhydride; andvinyl ether monomers.

Preferred fluorinated monomers which are useful in the processes of thepresent invention will contain at least one fluorine atom,perfluoroalkyl group, or perfluoroalkoxy group directly attached to thevinyl group that undergoes polymerization. Examples of suitablefluorinated monomers include, but are not limited to, perfluoroolefins,particularly tetrafluoroethylene, perfluoro(alkyl vinyl ethers) withperfluoroalkyl groups containing 1 to 6 carbon atoms and thosecontaining functional groups such as CF₂ ═CFOCF₂ CF(CF₃)OCF₂ CF₂ SO₂ Fand CF₂ ═CFOCF₂ CF(CF₃)OCF₂ CF₂ CO₂ CH₃, hexafluoropropylene,perfluoro(2,2-dimethyldioxole), cure site monomers such asbromotrifluoroethylene and partially fluorinated monomers, particularlyvinyl fluoride, vinylidene fluoride, chlorotrifluoroethylene, andperfluoroalkyl ethylenes with perfluoroalkyl groups containing 1 to 6carbon atoms. Preferred fluoromonomers include tetrafluoroethylene,hexafluoropropylene, perfluoromethylvinyl ether, perfluoroethylvinylether, perfluoropropylvinyl ether, vinyl fluoride, vinylidene fluoride,chlorotrifluoroethylene, and perfluoro(2,2-dimethyldioxole).

The polymers produced according to the processes of the presentinvention include homopolymers of any of the foregoing monomers, or inthe embodiment wherein two or more comonomers are employed, the polymersmay be copolymers. Exemplary homopolymers which may be producedaccording to the methods of the present invention include but are notlimited to polyethylene, polyvinylchloride, polymethyl methacrylate,polystyrene, polychlorotrifluoroethylene, polytetrafluoroethylene,polyvinylfluoride, polyvinylidenefluoride, and the like.

The polymerization process of the present invention may be carried outwith comonomers. The comonomers may be any of the hydrocarbon orfluorinated monomers described above, which are capable ofcopolymerizing. Any combination of copolymerizable monomers may beemployed to produce a water insoluble polymer, including copolymerizablehydrocarbon monomers and fluorinated monomers.

Copolymers which may be produced according to the processes of thepresent invention include but are not limited totetrafluoroethylene/hexafluoropropylene,tetrafluoroethylene/hexafluoropropylene/vinylidene fluoride,hexafluoropropylene/vinylidene fluoride, perfluoro(methyl vinylether)/vinylidene fluoride, perfluoro(methyl vinyl ether)/vinylidenefluoride/tetrafluoroethylene, chlorotrifluoroethylene/vinylidenefluoride, chlorotrifluoroethylene/ethylene,chlorotrifluoroethylene/tetrafluoroethylene/ethylene,tetrafluoroethylene/perfluoro(propyl vinyl ether),tetrafluoroethylene/perfluoro(methyl vinyl ether),tetrafluoroethylene/perfluoro(2,2-dimethyl-1,3-dioxole),tetrafluoroethylene/ethylene, tetrafluoroethylene/propylene,tetrafluoroethylene/CF₂ ═CFOCF₂ CF(CF₃)OCF₂ CF₂ SO₂ F,tetrafluoroethylene/CF₂ ═CFOCF₂ CF₂ SO₂ F,tetrafluoroethylene/hexafluoropropylene/perfluoro(propyl vinyl ether),styrene/butadiene, styrene/chloroprene, styrene/acylonitrile,acrylonitrile/butadiene, ethylene/vinyl acetate, chloroprene/methylmechacrylate, and chloroprene/acrylonitrile.

The initiator employed in the processes of the present invention may besoluble in the aqueous phase or insoluble in the aqueous phase.Initiators which are insoluble in the aqueous phase may be soluble incarbon dioxide or insoluble in both the aqueous phase and carbon dioxidesuch that the initiator forms a separate phase. Examples of suitableinitiators which are insoluble in the aqueous phase include but are notlimited to halogenated initiators and other hydrocarbon free radicalinitiators. Suitable halogenated initiators include, for example,chlorinated and fluorinated initiators. For example, suitablehalogenated polymerization initiators include chlorocarbon andfluorocarbon based acyl peroxides such as trichloroacetyl peroxide,bis(perfluoro-2-propoxy propionyl peroxide, [CF₃ CF₂ CF₂ OCF(CF₃)COO]₂ ;perfluoropropionyl peroxides, (CF₃ CF₂ CF₂ COO)₂, (CF₃ CF₂ COO)₂, {CF₃CF₂ CF₂)[CF(CF₃)CF₂ O]_(n) C_(F) (CF₃)COO}₂, [ClCF₂ (CF₂)_(n) COO]₂, and[HCF₂ (CF₂)_(n) COO]₂ where n=0-8; perfluoroalkyl azo compounds such asperfluoroazoisopropane, [(CF₃)₂ CFN═]2; R₄ N═NR₄, where R₄ is a linearor branched perfluorocarbon group having 1-8 carbons; stable or hinderedperfluoroalkane radicals such as hexafluoropropylene trimer radical,[(CF₃)₂ CF]₂ (CF₂ CF₃)C radical and perfluoroalkanes. Preferredhalogenated initiators include trichloroacetyl peroxide,bis(perfluoro-2-propoxy propionyl peroxide, perfluoropropionyl peroxide,perfluoroazoisopropane, and hexafluoropropylene trimer radical. Examplesof hydrocarbon free radical initiators include but are not limited toacetylcyclohexanesulfonyl peroxide, diacetyl peroxydicarbonate,dicyclohexyl peroxydicarbonate, di-2-ethylhexyl peroxydicarbonate,t-butyl perneodecanoate, 2,2'-azobis(methoxy-2,4-dimethylvaleronitrile), t-butyl perpivalate, dioxtanoylperoxide, dilauroyl peroxide, 2,2'-azobis(2,4-dimethylvaleronitrile),t-butylazo-2-cyanobutane, dibenzoyl peroxide, t-butylper-2-ethylhexanoate, t-butyl permaleate, 2,2'-azobis(isobutyronitrile),bis(t-butyl peroxy)cyclohexane, t-butyl peroxyisopropylcarbonate,t-butylperacetate, 2,2-bis(t-butylperoxy)butane,dicumyl peroxide,di-t-amyl peroxide, di-t-butyl peroxide, p-menthane hydroperoxide,pinane hydroperoxide, cumene hydroperoxide, and t-butyl hydroperoxide.Preferred hydrocarbon free radical initiators includeazobisisobutyronitrile ("AIBN"), dilauroyl peroxide, diisopropyl peroxydicarbamate, t-butyl hydroperoxide, di-t-butyl peroxide, and dicumylperoxide.

Initiators which are soluble in the aqueous phase include but are notlimited to inorganic peroxides such as hydrogen peroxide or persulfateion; potassium permanganate; disuccinic acid peroxide; and redoxinitiators such as alkali metal persulfates and bisulfates, ammoniumpersulfates, ferrous sulfates, silver nitrate, and cupric sulfate, orany combinations thereof.

The initiator may be added in neat form, or it may conveniently be addedas a solution in a co-solvent. Typically, the initiator is used in anamount conventionally employed for polymerization. For example, theinitiator may be used in an amount of about 10⁻⁶ to 10, preferably about10⁻⁵ to 2, parts by weight per 100 parts by weight monomer.

The processes of the present invention may also include a surfactant.Any suitable surfactant known to those skilled in the an may beemployed. Typical surfactants include anionic surfactants, cationicsurfactants, zwitterionic surfactants, non-ionic block and graftcopolymer surfactants and polymeric surfactants and stabilizers. Forexample, suitable polymeric stabilizers include, but are not limited topoly(vinyl alcohol), hydroxy propyl cellulose, sodium(styrenesulfonate), poly(ethylene oxide), and the sodium salt of poly(acrylicacid). Examples of useful anionic surfactants include but are notlimited to fatty acid soaps such as sodium or potassium stearate,laurate, and palmitate, sulfonates, sulfates, and fluorinatedsurfactants such as perfluoro-octanoic acid and salts thereof includingsodium and ammonium salts thereof. Examples of useful nonionicsurfactants includes surfactants from the pluronic family, SPAN™ family,or TWEEN™ family and poly(propyleneoxide)-g-poly(ethylene oxide).Examples of useful cationic surfactants include but are not limited tododecylammonium chloride and acetyltrimethyl ammonium bromide.

In addition, silicon and fluorocarbon surfactants are useful. Examplesinclude but are not limited to poly(1,1-dihydroperfluorooctyl acrylate)and random, block, and graft copolymers thereof,poly(1,1,2,2-tetrahydroperfluoroacrylates and methacrylates) and random,block, and graft copolymers thereof, polysiloxanes and block and graftcopolymers thereof, particularly those with hydrophillic ethylene oxidesegments.

The processes of the present invention may optionally include otheragents capable of modifying, regulating or controlling the physical orchemical properties of the resulting polymer. For example, one skilledin the art will appreciate that a chain transfer agent may be employedto regulate the molecular weight of the resulting polymer, thuscontrolling the physical and chemical properties thereof. Chain transferagents which may optionally be employed in the processes of the presentinvention include but are not limited to alcohols such as methanol,mercaptans such as ethyl and butyl mercaptan, sulfides such as butylsulfide, halogen containing species such as alkyl halides such as alkyliodides, perfluoroalkyl iodides, alkyl bromides, perfluoroalkylbromides, carbon tetrachloride, and chloroform, and alkanes such asethane and methyl cyclohexane.

It may be desirable to include compounds which accelerate thedecomposition of the initiator. Such compounds typically permit thepolymerization reaction to take place at lower pressures than wouldotherwise be required, thus permitting the methods of the presentinvention to be practiced in conventional fluoropolymerization reactors.Suitable compounds which accelerate decomposition are known to thoseskilled in the art and include but are not limited to, redox systems,sulfur dioxide, ultraviolet light and the like.

The polymerization reaction may be carried out at a temperature of about-50° C. up to about 200° C., and is typically carried out at atemperature of between about -20° C. and about 150° C. Suitableantifreeze agents, such as ethylene glycol may be added to the aqueousphase of the reaction mixture to avoid freezing the aqueous phase duringreactions which are conducted at temperatures below the freezing pointof the aqueous phase. The reaction may be carried out at a pressureranging from about 15 psi to about 45,000 psi, and is typically carriedout at a pressure of between about 500 psi and about 10,000 psi.

The polymerization can be carried out batchwise or continuously withthorough mixing of the reactants in any appropriately designed highpressure reaction vessel, or tubular reaction vessel. To remove the heatevolved during the polymerization, advantageously the pressure apparatusincludes a cooling system. Additional features of the pressure apparatusused in accordance with the invention include heating means such as anelectric heating furnace to heat the reaction mixture to the desiredtemperature and mixing means, i.e., stirrers such as paddle stirrers,impeller stirrers, or multistage impulse countercurrent agitators,blades, and the like.

The polymerization can be carried out, for example, by placing themonomer and initiator in the pressure apparatus and introducing carbondioxide and the aqueous phase. The reaction vessel is closed and thereaction mixture brought to the polymerization temperature and pressure.Alternatively, only a part of the reaction mixture may be introducedinto an autoclave and heated to the polymerization temperature andpressure, with additional reaction mixture being pumped in at a ratecorresponding to the rate of polymerization. In another possibleprocedure, some of the monomers are initially taken into the autoclavein the total amount of carbon dioxide and the monomers or comonomers arepumped into the autoclave together with the initiator at the rate atwhich the polymerization proceeds.

When the polymerization is complete the polymer may be separated fromthe reaction mixture. Any suitable means of separating the polymer fromthe carbon dioxide and aqueous phase may be employed. Typically,according to the process of the present invention, the polymer isseparated from the reaction mixture by venting the carbon dioxide to theatmosphere. Thereafter the polymer may be collected simply by physicalisolation.

The polymers produced according to the processes of the presentinvention are useful as thermoplastics and elastomers which are usefulfor the manufacture of adhesives and molded articles such as valves,bottles, films, fibers, resins, and matrices. The fluoropolymers inparticular have applications in areas where conventional fluoropolymersare employed, and particularly as wire coatings, gaskets, seals, hoses,vessel linings, elastomers, molded resins, protective coatings, and thelike.

The following examples are provided to illustrate the present invention,and should not be construed as limiting thereof. In these examples, Kgmeans kilograms, g means grams, mg means milligrams, L means liters, mLmeans milliliters, J means Joules, J/g means Joules per gram, mol meansmole(s), Kg/mol means kilograms per mole, rpm means revolutions perminute, TFE means tetrafluoroethylene, CO₂ means carbon dioxide, K₂ S₂O₈ means potassium persulfate, DSC means Differential ScanningCalorimetry, and °C. means degrees Centigrade. Molecular weightestimated using the method described in T. Suwa, et al., J. AppliedPolymer Sci. 17:3253 (1973).

EXAMPLE 1

To a 25-mL stainless steel reaction vessel equipped with a horizontalpaddle type stirrer is added 25 mg K₂ S₂ O₈, 10 mL water and 25 mgperfluorooctanoic acid. The cell is cooled to well below 0° C. and 10 gof a 50:50 mixture of TFE:CO₂ (5 g TFE, 5 g CO₂) is condensed in underpressure. The reactor is gradually warmed to 50° C. Stirring is startedas soon as the ice in the cell melts allowing the stirrer to rotatefreely. Stirring is maintained for 24 hours at 50° C. before thepressure is vented from the cell, the cell opened and the contentsrecovered. The reaction yields 3.6 g of product (72% yield) DSC analysisyields a virgin melting point of 329.9° C., a second melt of 330.0° C.and a heat of crystallization of -60.9 J/g (2nd heat) corresponding toan estimated number average molecular weight of 20 Kg/mol.

EXAMPLE 2

To a 25-mL stainless steel reaction vessel equipped with a horizontalpaddle type stirrer is added 25 mg K₂ S₂ O₈, 10 mL water and 25 mgsodium perfluorooctanoate. The cell is cooled to well below 0° C. and 10g of a 50:50 mixture of TFE:CO₂ (5 g TFE, 5 g CO₂) is condensed in underpressure. The reactor is gradually warmed to 50° C. Stirring is startedas soon as the ice in the cell melts, allowing the stirrer to rotatefreely. Stirring is maintained for 24 hours at 50° C. before thepressure is vented from the cell, the cell opened and the contentsrecovered. The reaction yields 4.1 g of product (82% yield). DSCanalysis yields a virgin melting point of 330.0° C., a second melt of329.9° C. and a heat of crystallization of -60.9 J/g (2nd melt)corresponding to an estimated number average molecular weight of 20Kg/mol.

EXAMPLE 3

To a 25-mL stainless steel reaction vessel equipped with a horizontalpaddle type stirrer is added 2.9 mg K₂ S₂ O₈ and 10 mL water. The cellis cooled to well below 0° C. and 8.2 g of a 50:50 mixture of TFE:CO₂(4.1 g TFE, 4.1 g CO₂) is condensed in under pressure. The reactor isgradually warmed to 80° C. Stirring is started as soon as the ice in thecell melts, allowing the stirrer to rotate freely. Stirring ismaintained for 3 hours at 80° C. before the pressure is vented from thecell, the cell opened and the contents recovered. The reaction yields2.0 g of product (49% yield). DSC analysis yields a virgin melting pointof 334.7° C., a second melt of 333.1° C. and a heat of crystallizationof -50.8 J/g (2nd melt) corresponding to an estimated number averagemolecular weight of 60 Kg/mol.

EXAMPLE 4

To a 25-mL stainless steel reaction vessel equipped with a horizontalpaddle type stirrer are added 0.29 mg K₂ S₂ O₈ and 10 mL water. The cellis cooled to well below 0° C. and 10.5 g of a 50:50 mixture of TFE:CO₂(5.2 g TFE, 5.2 g CO₂) is condensed in under pressure. The reactor isgradually warmed to 75° C. Stirring is started as soon as the ice in thecell melts allowing the stirrer to rotate freely. Stirring is maintainedfor 7 hours at 75° C. before the pressure is vented from the cell, thecell opened and the contents recovered. The reaction yields 0.37 g (7.0%yield.). DSC analysis yields a virgin melting point of 337.7° C., asecond melt of 331.2° C. and a heat of crystallization of -40.6 J/g (2ndmelt) corresponding to an estimated number average molecular weight of170 Kg/mol.

EXAMPLE 5

To a 25-mL stainless steel reaction vessel equipped with a horizontalpaddle type stirrer is added 0.49 mg K₂ S₂ O₈ and 10 mL water. The cellis cooled to well below 0° C. and 11.5 g of a 50:50 mixture of TFE:CO₂(5.7 g TFE, 5.7 g CO₂) is condensed under pressure. The reactor isgradually warmed to 75° C. Stirring is started as soon as the ice in thecell melts allowing the stirrer to rotate freely. Stirring is maintainedfor 17 hours at 75° C. before the pressure is vented from the cell, thecell opened and the contents recovered. The reaction yields 2.5 g ofproduct (43% yield). DSC analysis yields a virgin melting point of338.3° C., a second melt of 327.7° C. and a heat of crystallization of-37.7 J/g (2nd melt) corresponding to an estimated number averagemolecular weight of 260 Kg/mol.

EXAMPLE 6

To a 25-mL stainless steel reaction vessel equipped with a horizontalpaddle type stirrer is added 0.11 mg K₂ S₂ O₈ and 10 mL water. The cellis cooled to well below 0° C. and 11.7 g of a 50:50 mixture of TFE:CO₂(5.8 g TFE, 5.8 g CO₂) is condensed in under pressure. The reactor isgradually warmed to 75° C. Stirring is started as soon as the ice in thecell melts allowing the stirrer to rotate freely. Stirring is maintainedfor 17 hours at 75° C. before the pressure is vented from the cell, thecell opened and the contents recovered. The reaction yields 0.7 g (12%yield). DSC analysis of this product yields a virgin melting point of334.9° C., a second melt of 327.0° C. and, a heat of crystallization of-28.0 J/g (2nd melt) corresponding to an estimated number averagemolecular weight of 1,160 Kg/mol.

EXAMPLE 7

A 600-mL stainless steel Autoclave equipped with a stirrer agitation isseasoned with a solution of persulfate in water by heating to ca. 90° C.and filling with 500 mL of a solution of initiator (ca. 0.5 g ammoniumpersulfate in 500 mL water) and then heating for a couple of hours. Thisprocedure is repeated twice before running the polymerization.

To the seasoned reactor is added 0.8 mg K₂ S₂ O₈ and 250 mL water. TheAutoclave is cooled to well below 0° C. and 53.0 g of a 50:50 mixture ofTFE:CO₂ (26.5 g TFE, 26.5 g CO₂) is condensed in under pressure. Thereactor is gradually warmed to 75° C. Stirring is started at ca. 1000rpm as soon as the ice in the cell melts allowing the stirrer to rotatefreely. Stirring is maintained for 5 hours at 75° C. before the pressureis vented from the cell, the cell opened and the contents recovered. Thereaction yields 24 g of product (90% yield). DSC analysis of thisproduct yields a virgin melting point of 338.6° C., a second melt of328.5° C. and a heat of crystallization of -29.4 J/g (2nd melt)corresponding to an estimated number average molecular weight of 900Kg/mol.

EXAMPLE 8

A 600-mL stainless steel Autoclave equipped with a stirrer is seasonedwith a solution of persulfate in water by heating to ca. 90° C. and thenfilling with 500 mL of a solution of initiator (ca. 0.5 g ammoniumpersulfate in 500 mL water) and then heating for a couple of hours. Thisprocedure is repeated twice before running the polymerization.

To the seasoned reactor is added 2.6 mg K₂ S₂ O₈ and 250 mL water. TheAutoclave is cooled to well below 0° C. and 50.1 g of a 50:50 mixture ofTFE:CO₂ (25 g TFE, 25 g CO₂) is condensed in under pressure. The reactoris gradually warmed to 75° C. Stirring is started at ca. 1000 rpm assoon as the ice in the cell melts allowing the stirrer to rotate freely.Stirring is maintained for 5 hours at 75° C. before the pressure isvented from the cell, the cell opened and the contents recovered. Thereaction yields 22.6 g of product (90% yield). DSC analysis yields avirgin melting point of 336.7° C., a second melt of 329.4° C. and a heatof crystallization of 38.2 J/g (2nd melt) corresponding to an estimatednumber average molecular weight if 235 Kg/mol.

EXAMPLE 9

A 600-mL stainless steel Autoclave equipped with a stirrer is seasonedwith a solution of persulfate in water by heating to ca. 90° C., thenfilling with 500 mL of a solution of initiator (ca. 0.5 g ammoniumpersulfate in 500 mL water), and then heating for a couple of hours.This procedure is repeated twice before running the polymerization.

To the seasoned reactor is added 3.2 mg K₂ S₂ O₈, 10 mg ammoniumperfluorooctanoate, and 250 mL water. The Autoclave is cooled to wellbelow 0° C. and 51 g of a 50:50 mixture of TFE:CO₂ (25.5 g TFE, 25.5 gCO₂) is condensed in under pressure. The reactor is gradually warmed to75° C. Stirring is started at ca. 1000 rpm as soon as the ice in thecell melts allowing the stirrer to rotate freely. Stirring is maintainedfor 5 hours at 75° C. before the pressure is vented from the cell, thecell opened and the contents recovered. The reaction yields 20.9 g ofproduct (82% yield). DSC analysis yields a virgin melting point of338.6° C., a second melt of 330.3° C. and a heat of crystallization of35.3 J/g (2nd melt) corresponding to an estimated number averagemolecular weight if 350 Kg/mol.

EXAMPLE 10

A 600-mL stainless steel Autoclave equipped with a stirrer is seasonedwith a solution of persulfate in water by heating to ca. 90° C., thenfilling with 500 mL of a solution of initiator (ca. 0.5 g ammoniumpersulfate in 500 mL water), and then heating for a couple of hours.This procedure is repeated twice before running the polymerization.

To the seasoned reactor is added 0.8 mg K₂ S₂ O₈, 10 mg ammoniumperfluorooctanoate, and 250 mL water. The Autoclave is cooled to wellbelow 0° C. and 50.9 g of a 50:50 mixture of TFE:CO₂ (25.4 g TFE, 25.4 gCO₂) is condensed in under pressure. The reactor is gradually warmed to75° C. Stirring is started at ca. 1000 rpm as soon as the ice in thecell melts allowing the stirrer to rotate freely. Stirring is maintainedfor 5 hours at 75° C. before the pressure is vented from the cell, thecell opened and the contents recovered. The reaction yields 21.7 g ofproduct (85% yield). DSC analysis yields a virgin melting point of344.1° C., a second melt of 328.5° C. and a heat of crystallization of35.3 J/g (2nd melt) corresponding to an estimated number averagemolecular weight if 350 Kg/mol.

EXAMPLE 11

To a 25-mL stainless steel reaction vessel equipped with a horizontalpaddle type stirrer is added 0.04 mL di(tert-butyl)peroxide, 0.11 mLmethyl cyclohexane (as a chain transfer agent), and 8 mL water. The cellis cooled to well below 0° C. and 6.8 g of a 50:50 mixture of TFE:CO₂(3.4 g TFE, 3.4 g CO₂) is condensed in under pressure, followed by anaddition of 3.5 g of CO₂. The reactor is gradually warmed to 140° C.Stirring is started as soon as the ice in the cell melts allowing thestirrer to rotate freely. Stirring is maintained for 4 hours at 140° C.before the pressure is vented from the cell, the cell opened and thecontents recovered. The reaction yields 1.1 g of low molecular weightpolytetrafluoroethylene (37% yield).

EXAMPLE 12

Ethylene is polymerized in mixed medium consisting of water and carbondioxide according to the method of Example 7 employing a water solubleinitiator such as ammonium persulfate in the absence of surfactant. Oneskilled in the art will appreciate that other water soluble initiatorsand surfactants may be employed.

EXAMPLE 13

Vinyl chloride is polymerized in mixed medium consisting of water andcarbon dioxide according to the method of Example 7 employing a watersoluble initiator such as ammonium persulfate in the absence ofsurfactant. One skilled in the art will appreciate that other watersoluble initiators and surfactants may be employed.

EXAMPLE 14

Methyl methacrylate is polymerized in mixed medium consisting of waterand carbon dioxide employing a water soluble initiator such as ammoniumpersulfate according to the method of Example 7 in the absence ofsurfactant. One skilled in the art will appreciate that other watersoluble initiators and surfactants may be employed.

EXAMPLE 15

Styrene is polymerized in mixed medium consisting of water and carbondioxide employing a water soluble initiator such as ammonium persulfateaccording to Example 7 in the absence of surfactant. One skilled in theart will appreciate that other water soluble initiators and surfactantsmay be employed.

EXAMPLE 16

Ethylene is polymerized in mixed medium consisting of water and carbondioxide according to the method of Example 11 employing a waterinsoluble initiator such as AIBN in the absence of surfactant. Oneskilled in the art will appreciate that other water insoluble initiatorsand surfactants may be employed.

EXAMPLE 17

Vinyl chloride is polymerized in mixed medium consisting of water andcarbon dioxide according to the method of Example 11 employing a waterinsoluble initiator such as AIBN in the absence of surfactant. Oneskilled in the art will appreciate that other water insoluble initiatorsand surfactants may be employed.

EXAMPLE 18

Methyl methacrylate is polymerized in mixed medium consisting of waterand carbon dioxide according to the method of Example 11 employing awater insoluble initiator such as AIBN in the absence of surfactant. Oneskilled in the art will appreciate that other water insoluble initiatorsand surfactants may be employed.

EXAMPLE 19

Styrene is polymerized in mixed medium consisting of water and carbondioxide according to the method of Example 11 employing a waterinsoluble initiator such as AIBN in the absence of surfactant. Oneskilled in the art will appreciate that other water insoluble initiatorsand surfactants may be employed.

EXAMPLE 20

Ethylene and vinyl acetate are copolymerized in mixed medium consistingof water and carbon dioxide according to the method of Example 11employing a water insoluble initiator such as AIBN, both in the presenceand in the absence of surfactant. One skilled in the art will appreciatethat other water insoluble initiators and surfactants may be employed.

EXAMPLE 21

Ethylene and vinyl acetate are copolymerized in mixed medium consistingof water and carbon dioxide according to the method of Example 7employing a water soluble initiator such as ammonium persulfate, both inthe presence and in the absence of surfactant. One skilled in the artwill appreciate that other water soluble initiators and surfactants maybe employed.

EXAMPLE 22

Chloroprene is polymerized in mixed medium consisting of water andcarbon dioxide according to the method of Example 11 employing a waterinsoluble initiator such as AIBN, both in the presence and in theabsence of surfactant. One skilled in the art will appreciate that otherwater insoluble initiators and surfactants may be employed.

EXAMPLE 23

Chloroprene is polymerized in mixed medium consisting of water andcarbon dioxide according to the method of Example 7, employing a watersoluble initiator such as ammonium persulfate, both in the presence andin the absence of surfactant. One skilled in the art will appreciatethat other water soluble initiators and surfactants may be employed.

EXAMPLE 24

Chloroprene and styrene are copolymerized in mixed medium consisting ofwater and carbon dioxide according to the method of Example 11 employinga water insoluble initiator such as AIBN, both in the presence and inthe absence of surfactant. One skilled in the art will appreciate thatother water insoluble initiators and surfactants may be employed.

EXAMPLE 25

Chloroprene and styrene are copolymerized in mixed medium consisting ofwater and carbon dioxide according to the method of Example 7, employinga water soluble initiator such as ammonium persulfate, both in thepresence and in the absence of surfactant. One skilled in the art willappreciate that other water soluble initiators and surfactants may beemployed.

EXAMPLE 26

Chloroprene and methyl methacrylate are copolymerized in mixed mediumconsisting of water and carbon dioxide according to the method ofExample 11 employing a water insoluble initiator such as AIBN, both inthe presence and in the absence of surfactant. One skilled in the artwill appreciate that other water insoluble initiators and surfactantsmay be employed.

EXAMPLE 27

Chloroprene and methyl methacrylate are copolymerized in mixed mediumconsisting of water and carbon dioxide according to the method ofExample 7 employing a water soluble initiator such as ammoniumpersulfate, both in the presence and in the absence of surfactant. Oneskilled in the art will appreciate that other water soluble initiatorsand surfactants may be employed.

EXAMPLE 28

Chloroprene and acrylonitrile are copolymerized in mixed mediumconsisting of water and carbon dioxide according to the method ofExample 11 employing a water insoluble initiator such as AIBN, both inthe presence and in the absence of surfactant. One skilled in the artwill appreciate that other water insoluble initiators and surfactantsmay be employed.

EXAMPLE 29

Chloroprene and acrylonitrile are copolymerized in mixed mediumconsisting of water and carbon dioxide according to the method ofExample 7 employing a water soluble initiator such as ammoniumpersulfate, both in the presence and in the absence of surfactant. Oneskilled in the art will appreciate that other water soluble initiatorsand surfactants may be employed.

The foregoing is illustrative of the present invention and is not to beconstrued as limiting thereof. The invention is defined by the followingclaims, with equivalents of the claims to be included therein.

That which is claimed is:
 1. A multi-phase polymerization process formaking a water insoluable polymer, said process comprising:providing apolymerization reaction mixture comprising a carbon dioxide phase and aseparate aqueous phase, said mixture containing a monomer and apolymerization initiator capable of initiating the polymerization ofsaid monomer, wherein said monomer is selected from the group consistingof hydrocarbon monomers and flourinated monomers; and polymerizing saidmonomer in said polymerization reaction mixture to produce said waterinsoluable polymer.
 2. The process according to claim 1, wherein saidpolymerization initiator is solubilized in said aqueous phase.
 3. Theprocess according to claim 1, wherein said polymerization initiator isinsoluble in said aqueous phase.
 4. The process according to claim 3,wherein said polymerization initiator is solubilized in said carbondioxide.
 5. The process according to claim 3, wherein saidpolymerization initiator is insoluble in said aqueous phase andinsoluble in said carbon dioxide and forms a separate phase in saidpolymerization reaction mixture.
 6. The process according to claim 1,wherein said monomer is a hydrocarbon monomer selected from the groupconsisting of vinyl monomers, diene monomers, styrene monomers, acrylicmonomers, acrylate monomers, and vinyl ether monomers.
 7. The processaccording to claim 1, wherein said monomer is a hydrocarbon monomerselected from the group consisting of vinyl chloride, vinyl acetate,ethylene, propylene, acrylonitrile, isoprene, chloroprene, butadiene,styrene, t-butyl styrene, alkyl(meth)acrylates, acrylamide, maleicanhydride, and vinyl ether monomers.
 8. The process according to claim1, wherein said monomer is a fluorinated monomer selected from the groupconsisting of monomers having at least one fluorine bound to a vinylcarbon, monomers having at least one perfluoroalkyl group bound to avinyl carbon, and monomers having at least one perfluoroalkoxy groupbound to a vinyl carbon.
 9. The process according to claim 1, whereinsaid monomer is a fluorinated monomer selected from the group consistingof perfluoroolefins, and perfluoro(alkyl vinyl ethers).
 10. The processaccording to claim 1, wherein said monomer is a fluorinated monomerselected from the group consisting of tetrafluoroethylene,hexafluoropropylene, perfluoromethylvinyl ether, perfluoroethylvinylether, perfluoropropylvinyl ether, vinyl fluoride, vinylidene fluoride,chlorotrifluoroethylene, and perfluoro(2,2-dimethyl dioxole).
 11. Theprocess according to claim 1, wherein said polymerization initiator isselected from the group consisting of inorganic peroxide initiators, andredox initiators, soluble in said aqueous phase.
 12. The processaccording to claim 1, wherein said polymerization initiator is selectedfrom the group consisting of halogenated initiators and hydrocarbon freeradical initiators, insoluble in said aqueous phase.
 13. The processaccording to claim 1, wherein said carbon dioxide is liquid carbondioxide.
 14. The process according to claim 1, wherein said carbondioxide is gaseous carbon dioxide.
 15. The process according to claim 1,wherein said carbon dioxide is supercritical carbon dioxide.
 16. Theprocess according to claim 1, wherein said process is carried out in thepresence of a surfactant.
 17. The process according to claim 1, furthercomprising the step of separating said polymer from said mixture andcollecting said polymer.
 18. The process according to claim 17, whereinsaid step of separating said polymer from said mixture comprises ventingsaid carbon dioxide phase to the atmosphere.
 19. The process accordingto claim 1, wherein said process is carried out in the presence of achain transfer agent.
 20. The process according to claim 1 furthercomprising adding a comonomer to said reaction mixture, and saidpolymerizing step comprises copolymerizing said monomer with saidcomonomer.
 21. The process according to claim 20, wherein said comonomeris selected from the group consisting of fluorinated and non-fluorinatedcomonomers.
 22. The process according to claim 20, wherein saidcomonomer is selected from the group consisting of tetrafluoroethylene,hexafluoropropylene, perfluoromethylvinyl ether, perfluoroethylvinylether, perfluoropropylvinyl ether, vinyl fluoride, vinylidene fluoride,chlorotrifluoroethylene, and perfluoro(2,2-dimethyl dioxole), vinylchloride, vinyl acetate, vinyl ether, ethylene, propylene,acrylonitrile, isoprene, chloroprene, butadiene, styrene, t-butylstyrene, acrylate, alkyl(meth)acrylate, acrylamide, and maleicanhydride.